Refrigerator and control method thereof

ABSTRACT

A refrigerator and control method thereof, the refrigerator including a main body having a plurality of storage compartments, a compressor and a condenser which are provided in the main body, a plurality of evaporators corresponding to the respective storage compartments, a main refrigerant pipe to connect the compressor, the condenser and the evaporators in series, at least one branch refrigerant pipe which is branched between the condenser and one of the evaporators to be connected with an inlet of one of the remaining evaporators, and a selection valve which is provided on a branching point of the at least one branch refrigerant pipe to open and close the main refrigerant pipe and the at least one branch refrigerant pipe, respectively. The refrigerator adjusts a flow of a refrigerant flowing through respective evaporators according to preset temperatures of respective storage compartments in a refrigerator.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of Korean Patent Application No. 10-2005-0086773, filed on Sep. 16, 2005, in the Korean Intellectual Property Office, the disclosure of which is incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a refrigerator and a control method thereof. More particularly, to a refrigerator including a main body having a plurality of storage compartments, and a plurality of evaporators corresponding to the respective storage compartments, and a control method thereof.

2. Description of the Related Art

Generally, a conventional refrigerator keeps food at low temperatures. The conventional refrigerator includes a main body having a plurality of storage compartments to store food therein, a door which opens and closes an opening formed on the plurality of storage compartments, and a cooling system which is provided in the main body to cool the storage compartments.

The cooling system includes a compressor, a condenser, a decompressor and an evaporator. Recently, a plurality of evaporators is provided to independently supply cooling air to the plurality of storage compartments, corresponding to the respective storage compartments.

FIG. 1 illustrates an example of a conventional independent cooling type refrigerator which includes a cooling system having a plurality of evaporators connected with each other in series, corresponding to a plurality of storage compartments.

Referring to FIG. 1, the conventional independent cooling type cooling system 101 comprises a compressor 111, a condenser 112, a first evaporator 141 and a second evaporator 151 which are provided corresponding to a first storage compartment 140 and a second storage compartment 150 having different preset temperatures with each other, and a decompressor 120 which decompresses a refrigerant introduced to the respective evaporators 141 and 151.

The conventional refrigerator allows the refrigerant to circulate the compressor 111, the condenser 112, the decompressor 120 and the first and second evaporators 141 and 151 sequentially, when performing a cooling operation. The cooling air generated by the respective evaporators 141 and 151 is supplied to the respective storage compartments 140 and 150 through cooling fans 143 and 153 provided corresponding to the respective evaporators 141 and 151.

When an internal temperature of either the first storage compartment 140 or the second storage compartment 150 satisfies the preset temperature, the conventional refrigerator stops operating the cooling fans 143 and 153 of the respective storage compartments 140 and 150, thereby preventing food stored in the first and second storage compartments 140 and 150 from being overcooled.

However, in the independent cooling system 101 of the conventional refrigerator, since the plurality of evaporators are connected with each other in series, the refrigerant continuously flows in the evaporators of the respective storage compartments 140 and 150 even when one of the first and second storage compartments 140 and 150 satisfies the preset temperature and the cooling fans stop operating.

Accordingly, the refrigerant circulates both the first and second evaporators 141 and 151 even when a single storage compartment (i.e., the first or second storage compartments 140, 150) needs to be cooled, thereby lowering the temperature of the first or second evaporators 141 or 151 which is not required to generate the cooling air and possibly forming a frost on the respective evaporator.

Also, as the refrigerant passes the decompressor 120 in a refrigerant circulating path, it is decompressed unnecessarily. Further, power consumption increases as the refrigerant is compressed in the compressor 111 as much as the decompressed amount of the refrigerant.

SUMMARY OF THE INVENTION

Accordingly, it is an aspect of the present invention to provide a refrigerator which adjusts a flow of a refrigerant flowing through respective evaporators of the refrigerator, according to preset temperatures of respective storage compartments in the refrigerator having a plurality of storage compartments and a plurality of evaporators corresponding to the respective storage compartments, and a control method thereof.

Additional aspects and/or advantages of the present invention will be set forth in part in the description which follows and, in part, will be apparent from the description, or may be learned by practice of the present invention.

The foregoing and/or other aspects of the present invention are achieved by providing a refrigerator having a main body including a plurality of storage compartments, a compressor and a condenser which are provided in the main body, the refrigerator including a plurality of evaporators which are provided corresponding to the respective storage compartments, a main refrigerant pipe to connect the compressor, the condenser and the evaporators in series, at least one branch refrigerant pipe which is branched between the condenser and one of the evaporators to be connected with an inlet of one of the remaining evaporators, and a selection valve which is provided on a branching point of the at least one branch refrigerant pipe to open and close the main refrigerant pipe and the respective branch refrigerant pipe, respectively.

According to another aspect of the present invention, the refrigerator further includes a plurality of inner temperature sensors which sense inner temperatures of the respective storage compartments, and a controller which controls the selection valve not to supply refrigerant to the evaporator corresponding to a respective storage compartment, when the respective storage compartment satisfies a preset temperature, when sensed by the respective inner temperature sensor.

According to another aspect of the present invention, preset temperatures of the storage compartments are lowered in sequence, and the evaporators are connected with the main refrigerant pipe in series corresponding to the respective storage compartments.

According to another aspect of the present invention, the storage compartments include first, second and third storage compartments, and the evaporators include first, second and third evaporators which are connected with the main refrigerant pipe in series corresponding to the first, second and third storage compartments, respectively.

According to another aspect of the present invention, the at least one branch refrigerant pipe includes a first branch refrigerant pipe which is branched from the branching point to be connected with an inlet of the second evaporator, and a second branch refrigerant pipe which is branched from the branching point to be connected with an inlet of the third evaporator.

According to another aspect of the present invention, the controller controls the selection valve to open the main refrigerant pipe and close the first and second branch refrigerant pipes, when the respective storage compartments perform a cooling operation, to close the main refrigerant pipe and the second branch refrigerant pipe and open the first branch refrigerant pipe when the first storage compartment satisfies the preset temperature, and to close the main refrigerant pipe and the first branch refrigerant pipe and open the second branch refrigerant pipe when the second storage compartment satisfies the preset temperature, when sensed by the inner temperature sensors of the first and second storage compartments.

According to another aspect of the present invention, the refrigerator further comprises a plurality of decompressors to decompress refrigerant circulating respective evaporators. The decompressors including a first decompressor which is provided between the branching point and the first evaporator, a second decompressor which is provided on the first branch refrigerant pipe and a third decompressor which is provided on the second branch refrigerant pipe, wherein the respective decompressors are provided to sequentially increase resistances according to a sequence of the first, second and third decompressors.

According to another aspect of the present invention, the refrigerator further comprises a fourth decompressor which is provided between the first and second evaporators.

According to another aspect of the present invention, the refrigerator further comprises a fifth decompressor which is provided between the second and third evaporators.

According to another aspect of the present invention, a total sum of resistances of the first and fourth decompressors is smaller than that of the second decompressor.

According to another aspect of the present invention, a total sum of resistances of the first, fourth and fifth decompressors is smaller than that of the third decompressor.

According to another aspect of the present invention, each decompressor includes a capillary tube.

According to another aspect of the present invention, the controller controls the selection valve to open the main refrigerant pipe and the first and second branch refrigerant pipes when the respective storage compartments perform the cooling operation, to close the main refrigerant pipe and open the first and second branch refrigerant pipes when the first storage compartment satisfies the preset temperature, and to close the main refrigerant pipe and the first branch refrigerant pipe and open the second branch refrigerant pipe when the second storage compartment satisfies the preset temperature, when sensed by the inner temperature sensors of the first and second storage compartments.

The foregoing and/or other aspects of the present invention are also achieved by providing a refrigerator including a compressor and a condenser, the refrigerator including first, second and third evaporators, a branching part which is provided at an outlet of the condenser, a first refrigerant path which is branched from the branching part to be connected with the first, second and third evaporators in series, a second refrigerant path which is branched from the branching part to be connected with the second and third evaporators in series; and a third refrigerant path which is branched from the branching part to be connected with the third evaporator.

According to another aspect of the present invention, the first, second and third refrigerant paths include first, second and third decompressors, respectively, of which resistances are increased in sequence.

According to another aspect of the present invention, the refrigerator further including a fourth decompressor which is provided between the first evaporator and the second evaporator, and a fifth decompressor which is provided between the second evaporator and the third evaporator, and wherein a resistance of the second decompressor is larger than a total sum of resistances of the first and fourth decompressors.

The foregoing and/or other aspects of the present invention are also achieved by providing a method of controlling a refrigerator having a main body which comprises a plurality of storage compartments of which preset temperatures are lowered in sequence, a compressor and a condenser which are provided in the main body, and a plurality of evaporators which are provided corresponding to the respective storage compartments, the method comprising providing a main refrigerant pipe connecting the first, second and third evaporators are connected in series, and at least one branch refrigerant pipe which is branched from an inlet of the first evaporator to be connected with an inlet of one of the second and third evaporators, sensing inner temperatures of the respective storage compartments, and opening and closing the main refrigerant pipe and the at least one branch refrigerant pipe not to supply refrigerant to the evaporator corresponding to a respective storage compartment, when the sensed inner temperature of the respective storage compartment satisfies a preset temperature thereof.

According to another aspect of the present invention, the providing the at least one branch refrigerant pipe includes providing a first branch refrigerant pipe which is branched from the inlet of the first evaporator to be connected with an inlet of the second evaporator, and a second branch refrigerant pipe which is branched from a branching point of the first branch refrigerant pipe to be connected with an inlet of the third evaporator.

According to another aspect of the present invention, the opening and closing the main refrigerant pipe and respective branch refrigerant pipes includes opening the main refrigerant pipe and closing the first and second branch refrigerant pipes when the compressor is driven, closing the main refrigerant pipe and the second branch refrigerant pipe and opening the first branch refrigerant pipe when the sensed inner temperature of the first storage compartment satisfies a preset temperature thereof, and closing the main refrigerant pipe and the first branch refrigerant pipe and opening the second branch refrigerant pipe, when the sensed inner temperature of the second storage compartment satisfies a preset temperature thereof.

According to another aspect of the present invention, the opening and closing the main refrigerant pipe and a respective branch refrigerant pipe includes providing a first decompressor which is provided at the inlet of the first evaporator, a second decompressor which is provided on the first branch refrigerant pipe and a third decompressor which is provided on the second branch refrigerant pipe, having resistances of the first, second and third decompressors that increase in sequence, opening the main refrigerant pipe and the first and second branch refrigerant pipes when the compressor is driven, closing the main refrigerant pipe and opening the first and second branch refrigerant pipes when the sensed inner temperature of the first storage compartment satisfies a preset temperature thereof, and closing the main refrigerant pipe and the first branch refrigerant pipe and opening the second branch refrigerant pipe, when the sensed temperature of the second storage compartment satisfies a preset temperature thereof.

A method of controlling a refrigerator having a plurality of storage compartments, a plurality of evaporators corresponding to the plurality of storage compartments, and a condenser and compressor, the method including setting preset temperatures for the storage compartments, connecting the evaporators, the condenser and the compressor in series via a main refrigerant pipe, connecting inlets of the evaporators to one another via at least one branch refrigerant pipe, sensing inner temperatures of the storage compartments, and opening and closing the main refrigerant pipe and the at least one branch refrigerant pipe to not supply refrigerant to a respective evaporator corresponding to a respective storage compartment when the sensed inner temperature of the respective storage compartment satisfies a preset temperature thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

These and/or other aspects and advantages of the present invention will become apparent and more readily appreciated from the following description of the embodiments, taken in conjunction with the accompanying drawings of which:

FIG. 1 illustrates a a cooling system of a conventional refrigerator;

FIG. 2 illustrates a a cooling system of a refrigerator according to an embodiment of the present invention;

FIG. 3 is a control flowchart illustrating a control method of a refrigerator according to an embodiment of the present invention; and

FIG. 4 is a control flowchart illustrating a control method of a refrigerator according to another embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Reference will now be made in detail to the embodiments of the present invention, examples of which are illustrated in the accompanying drawings, wherein like reference numerals refer to like elements throughout. The embodiments are described below to explain the present invention by referring to the figures.

As shown in FIG. 2, a refrigerator according to the present invention comprises a main body (not shown) having a plurality of storage compartments 40, 50 and 60, a cooling system 1 having a plurality of evaporators 41, 51 and 61 corresponding to the respective storage compartments 40, 50 and 60; a main refrigerant pipe 70 with which the plurality of evaporators 41, 51 and 61 are connected in series; one or more branch refrigerant pipes 71 and 73; and a selection valve 13 which is provided on a branching point of the branch refrigerant pipes 71 and 73, for example. However, the present invention is not limited to any particular number of storage compartments, evaporators, or branch refrigerant pipes, and may vary accordingly.

The refrigerator according to an embodiment of the present invention further comprises a plurality of inner temperature sensors 45, 55 and 65 which sense inner temperatures of the respective storage compartments 40, 50 and 60; and a controller 16 which controls the selection valve 13 according to a sensing result of the inner temperature sensors 45, 55 and 65.

The storage compartments 40, 50 and 60 are provided in the main body by partitioning the main body, to store food therein. As mentioned above, the storage compartments 40, 50 and 60 may be provided in various numbers, as necessary. When multiple storage compartments 40, 50 and 60 are provided, the respective storage compartments 40, 50 and 60 may have different preset temperatures with one another.

Hereinafter, as shown in FIG. 2, a refrigerator which comprises three storage compartments 40, 50 and 60 having different preset temperatures with one another will be described as an example of the present invention. For example, the preset temperatures of the first, second and third storage compartments are set as T1>T2>T3.

The cooling system 1 further comprises a compressor 11 which compresses a refrigerant, a condenser 12 which condenses the refrigerant compressed by the compressor 11, decompressors 21, 22, 23, 24 and 25 which decompress the condensed refrigerant to be supplied to the first, second and third evaporators 41, 51 and 61. The present invention is not limited to any particular number of decompressors, and may vary as necessary.

As shown in FIG. 2, the evaporators 41, 51 and 61 are provided corresponding to the respective storage compartments 40, 50 and 60. The refrigerant is evaporated and thus absorbs heat around the evaporators 41, 51 and 61 to generate cooling air. The evaporators 41, 51 and 61 may have different evaporation capabilities from one another corresponding to the preset temperatures of the respective storage compartments 40, 50 and 60. The cooling air generated by the evaporators 41, 51 and 61 is supplied to the respective storage compartments 40, 50 and 60 through cooling fans 43, 53 and 63 corresponding to the respective evaporators 41, 51 and 61.

The decompressors 21, 22, 23, 24 and 25 decompress the condensed refrigerant to be supplied to the evaporators 41, 51 and 61. Further, the decompressors 21, 22, 23, 24 and 25 may comprise capillary tubes or expansion valves, for example. However, the decompressors are not limited hereto and may vary, as necessary.

The decompressors 21, 22, 23, 24 and 25 may be plurally provided between the condenser 12 and the evaporators 41, 51 and 61, and between each of the respective evaporators 41, 51 and 61. Then, the respective decompressors 21, 22, 23, 24 and 25 each comprise different resistances from one another. The decompression capabilities of the decompressors 21, 22, 23, 24 and 25 are proportional to the resistances thereof. When the plurality of refrigerant pipes 70, 71 and 73 are open, the refrigerant flows much toward the decompressors 21, 22, 23, 24 and 25 with low resistance. The amount of the refrigerant is distributed by properly arranging the decompressors 21, 22, 23, 24 and 25 having different resistances from one another.

For example, when the second branch refrigerant pipe 73 is closed and the main refrigerant pipe 70 and the first branch refrigerant pipe 71 are simultaneously open, the first decompressor 21 and the fourth decompressor 24 are provided in the main refrigerant pipe 70 between the selection valve 13 and the second evaporator 51. The second decompressor 22 is provided in the first branch refrigerant pipe 71 between the selection valve 13 and the second evaporator 51. Here, when a total sum of the resistances of the first decompressor 21 and the fourth decompressor 24 is larger than that of the second decompressor 22, the refrigerant flows much to the main refrigerant pipe 70. When the main refrigerant pipe 70 is closed and the first and second branch refrigerant pipes 71 and 73 are simultaneously open, the resistance of the third decompressor 23 is larger than a total sum of the resistances of the second decompressor 22 and the fifth decompressor 25, thereby allowing the refrigerant flow much to the first branch refrigerant pipe 71.

The main refrigerant pipe 70 comprises a closed circuit in which the compressor 11, the condenser 12, the decompressors 21, 22, 23, 24 and 25 and the first, second and third evaporators 41, 51 and 61 are connected in series, to enable the refrigerant to circulate in sequence. The sequence of the evaporators 41, 51 and 61 connected with the main refrigerant pipe 70 in series corresponds to the sequence of the storage compartments 40, 50 and 60 of which preset temperatures are lowered in sequence. For example, when the cooling operation is performed, the first storage compartment 40 having the highest preset temperature satisfies the preset temperature, thereby sequentially bypassing the respective evaporators 41, 51 and 61 through the branch refrigerant pipes 71 and 73.

The branch refrigerant pipes 71 and 73 are branched between the condenser 12 and the first evaporator 41 which is provided next to the condenser 12 to be connected with one of the remaining evaporators 51 and 61. For example, when there are provided three evaporators 41, 51 and 61, the branch refrigerant pipes 71 and 73 the first branch refrigerant pipe 71 is branched from an inlet of the first evaporator 41 of the main refrigerant pipe 70 to be connected with the second evaporator 51, and the second branch refrigerant pipe 73 is branched from the inlet of the first evaporator 41 of the main refrigerant pipe 70 to be connected with the third evaporator 61.

The branch refrigerant pipes 71 and 73 bypass at least one of the evaporators 41, 51 and 61, to prevent unnecessary refrigerant supply to the corresponding evaporators 41, 51 and 61. For example, when the first storage compartment 40 satisfies the preset temperature, the refrigerant flows to the first branch refrigerant pipe 71, thereby bypassing the first evaporator 41 in order to be directly introduced to the second evaporator 51. Also, when the first and second storage compartments 40 and 50 satisfy the preset temperatures, the refrigerant flows to the second branch refrigerant pipe 73, thereby bypassing the first and the second evaporators 41 and 51 in order to be directly introduced to the third evaporator 61 after passing through the condenser 12.

The selection valve 13 is provided on the branching point of the respective branch refrigerant pipes 71 and 73, thereby opening and closing the main refrigerant pipe 70 and the branch refrigerant pipes 71 and 73, respectively. The selection valve 13 selectively opens one of the main refrigerant pipe 70, and the first and second branch refrigerant pipes 71 and 73, or simultaneously opens at least two of them. Meanwhile, the selection valve 13 may be manually controlled by a user, or by a controller 16.

The inner temperature sensors 45, 55 and 65 sense the inner temperatures of the respective storage compartments 40, 50 and 60. The inner temperature sensors 45, 55 and 65 correspond to the number of the respective storage compartments 40, 50 and 60. Therefore, the inner temperatures are not limited to any particular number and may vary according to the number of storage compartments. The inner temperatures of the respective storage compartments 40, 50 and 60 sensed by the inner temperature sensors 45, 55 and 65 are transmitted to the controller 16.

The controller 16 is provided in the main body. The controller 16 controls the selection valve 13 not to supply the refrigerant to the evaporators 41, 51 and 61 corresponding to the respective storage compartments 40, 50 and 61, when the inner temperatures reach the preset temperatures on the basis of comparison between the inner temperatures sensed by the inner temperature sensors 45, 55 and 65 and the preset temperatures of the respective storage compartments 40, 50 and 60.

The controller 16 controls the selection valve 13 to simultaneously open at least two of the main refrigerant pipe 70 and the first and second branch refrigerant pipes 71 and 73. Then, the refrigerant is properly distributed according to the resistances of the decompressors 21, 22, 23, 24 and 25 provided on the open refrigerant pipes 70, 71, 73.

In another embodiment of the present invention, a refrigerator comprises a branching part 14 provided on the branching point from which a main refrigerant pipe 70 starting from an outlet of a condenser 12 is branched. The branching part 14 comprises, for example, the main refrigerant pipe 70 (i.e.,a first refrigerant path) to which first, second and third evaporators 41, 51 and 61 are connected in series, a first refrigerant pipe 71 (i.e., a second refrigerant path) which is branched from the branching part 14 to be connected with the second and third evaporators 51 and 61 in series, and the second refrigerant pipe 73 (i.e., a third refrigerant path) which is branched from the branching part 14 to be connected with the third evaporator 61.

Then, the respective refrigerant paths 70, 71 and 73 comprise first, second and third decompressors 21, 22 and 23 with resistance increasing in sequence, thereby supplying the refrigerant according to resistance differences between the decompressors 21, 22 and 23, without a control of the selection valve 13.

Hereinbelow, a method of controlling a refrigerator according to the present invention will be described with reference to FIGS. 2, 3 and 4.

FIG. 3 is a flowchart illustrating a control method of a refrigerator according to an embodiment of the present invention, one of the main refrigerant pipe 70 and branch refrigerant pipes 71 and 73 is selectively open, and the others are closed by controlling a selection valve 13.

In operation 11, preset temperatures of respective storage compartments 40, 50 and 60 are input. The respective storage compartments 40, 50 and 60 may have different preset temperatures with one another. For example, the preset temperatures of the first, second and third storage compartments 40, 50 and 60 may be set as T1>T2>T3.

From operation 11, the process moves to operation 12, where a compressor 11 is driven to perform a cooling operation. Then, from operation 12, the process moves to operation 13, where temperatures of the respective storage compartments 40, 50 and 60 are sensed by inner temperature sensors 45, 55 and 65. From operation 13, the process moves to operation 14, where at an initial stage in which the cooling operation begins and the compressor 11 operates, only a main refrigerant pipe 70 is open, and branch refrigerant pipes 71 and 73 are closed, thereby allowing refrigerant to circulate all the evaporators 41, 51 and 61

From operation 14, the process moves to operation 15, where it is determined whether an inner temperature of the first storage compartment satisfies a preset temperature. When an inner temperature of the first storage compartment 40 having the highest preset temperature satisfies the preset temperature in operation 15, the process moves to operation 16, where a controller closes the main refrigerant pipe 70 not to supply the refrigerant to the first evaporator 41, and opens the first branch refrigerant pipe 71 to allow the refrigerant to circulate only the second evaporator 51 and the third evaporator 61. From operation 16, the process moves to operation 17, where it is determined whether an inner temperature of the second storage compartment 50 satisfies a preset temperature. When it is determined that the inner temperature of the second storage compartment 50 satisfies the preset temperature in operation 17, the process moves to operation 18, where the controller closes the first branch refrigerant pipe 71 and opens the second branch refrigerant pipe 73 alone, thereby allowing the refrigerant to be directly introduced to the third evaporator 61 without circulating the first and second evaporators 41 and 51. From operation 18, the process moves to operation 19, where it is determined whether an inner temperature of the third storage compartment satisfies a preset temperature. When it is determined that the inner temperature of the third storage compartment 60 satisfies the preset temperature in operation 19, the controller controls the compressor 11 to stop operating, thereby preventing the refrigerant from circulating.

As described above, in the control method of the refrigerator according to this embodiment of the present invention, the refrigerant is not supplied to the evaporators 41, 51 and 61 corresponding to the storage compartments 40, 50 and 60 which do not perform the cooling operation, among the plurality of storage compartments 40, 50 and 60, thereby preventing the temperatures of the evaporators 41, 51 and 61 from being lowered, a frost being generated, and power consumption due to low pressure operation of a cooling system.

FIG. 4 is a flowchart illustrating a control method of a refrigerator according to another embodiment of the present invention, where at least two of a main refrigerant pipe 70 and branch refrigerant pipes 71 and 73 are selectively open, and a remaining one thereof is closed through a control of a selection valve 13. Operations 31-33 perform similar functions as those of operations 11-13 shown in FIG. 3, therefore, a description of these operations is omitted herein.

Beginning at operation 34, at an initial stage of a cooling operation of respective storage compartments 40, 50 and 60, the main refrigerant pipe 70, the first branch refrigerant pipe 71 and the second branch refrigerant pipe 73 are open. As resistances of decompressors 21, 22, 23, 24 and 25 which are provided in the respective refrigerant pipes are different with one another, a refrigerant is distributed according thereto.

For example, when the resistances of the respective refrigerant pipes are set as [a first decompressor 21+a fourth decompressor 24+a fifth decompressor 25]<[a second decompressor 22+a fifth decompressor 25]<a third decompressor 23, the amount of the refrigerant controlled by the selection valve 13 is set as the main refrigerant pipe 70>the first branch refrigerant pipe 71>the second branch refrigerant pipe 73. Accordingly, the amount of the refrigerant passing through the second evaporator 51 is more than that of the refrigerant passing through the first evaporator 41. Also, the amount of the refrigerant passing through the third evaporator 61 is more than that of the refrigerant passing through the second evaporator 51.

From operation 34, the process moves to operation 35, where it is determined whether an inner temperature of the first storage compartment satisfies a preset temperature. When the inner temperature of the first storage compartment 40 satisfies the preset temperature in operation 35, the process moves to operation 36, where the main refrigerant pipe 70 is closed and the first branch refrigerant pipe 71 and the second branch refrigerant pipe 73 remain open. As a total sum of the resistances of the second decompressor 22 and the fifth decompressor 25 is larger than that of the second decompressor 22, the refrigerant is supplied much to the first branch refrigerant pipe 71.

From operation 36, the process moves to operation 37, where it is determined whether an inner temperature of the second storage compartment 50 satisfies a preset temperature. When the inner temperature of the second storage compartment 50 satisfies the preset temperature in operation 37, the process moves to operation 38, where the main refrigerant pipe 70 and the first branch refrigerant pipe 71 are closed and only the second branch refrigerant pipe 73 is open, thereby cooling the third storage compartment 60. From operation 38, the process moves to operation 39, where it is determined whether an inner temperature of the third storage compartment 60 satisfies a preset temperature. When it is determined that the inner temperature of the third storage compartment 60 satisfies the preset temperature in operation 39, the process moves to operation 40, the controller controls the compressor 11 to stop operating, thereby preventing the refrigerant from circulating.

In the control method of the refrigerator according to this embodiment of the present invention, the refrigerant is supplied according to the resistances of the decompressors 21, 22, 23, 24 and 25, thereby improving cooling speed. That is, at an initial operation, the amount of the refrigerant passing through the respective evaporators 41, 51 and 61 is set as the first evaporator 41<the second evaporator 51<the third evaporator 61. Then, the evaporator having the low preset temperature receives more refrigerant than the evaporator having the high preset temperature to concentrate cooling efficiency. Accordingly, the cooling operation time for all the storage compartments can be reduced, thereby shortening the driving time for the compressor 11 and reducing the power consumption.

Although a few embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that changes may be made in these embodiments without departing from the principles and spirit of the invention, the scope of which is defined in the appended claims and their equivalents. 

1. A refrigerator having a main body including a plurality of storage compartments, and a compressor and a condenser which are provided in the main body, the refrigerator comprising: a plurality of evaporators which are provided corresponding to the respective storage compartments; a main refrigerant pipe to connect the compressor, the condenser and the evaporators in series; at least one branch refrigerant pipe which is branched between the condenser and one of the evaporators to be connected with an inlet of one of the remaining evaporators; and a selection valve which is provided on a branching point of the at least one branch refrigerant pipe to open and close the main refrigerant pipe and the at least one branch refrigerant pipe, respectively.
 2. The refrigerator according to claim 1, the refrigerator further comprising: a plurality of inner temperature sensors which sense inner temperatures of the respective storage compartments; and a controller which controls the selection valve not to supply refrigerant to the evaporator corresponding to a respective storage compartment when the respective storage compartment satisfies a preset temperature when sensed by the respective inner temperature sensor.
 3. The refrigerator according to claim 2, wherein preset temperatures of the storage compartments are lowered in sequence, and wherein the evaporators are connected with the main refrigerant pipe in series corresponding to the storage compartments.
 4. The refrigerator of claim 3, wherein the storage compartments comprise first, second and third storage compartments of which preset temperatures are lowered in sequence, and wherein the evaporators comprise first, second and third evaporators which are connected with the main refrigerant pipe in series corresponding to the first, second and third storage compartments, respectively.
 5. The refrigerator according to claim 4, wherein the at least one branch refrigerant pipe comprises: a first branch refrigerant pipe which is branched from the branching point to be connected with an inlet of the second evaporator; and a second branch refrigerant pipe which is branched from the branching point to be connected with an inlet of the third evaporator.
 6. The refrigerator according to claim 5, wherein the controller controls the selection valve to open the main refrigerant pipe and close the first and second branch refrigerant pipes, when the respective storage compartments perform a cooling operation, to close the main refrigerant pipe and the second branch refrigerant pipe and open the first branch refrigerant pipe when the first storage compartment satisfies the preset temperature, and to close the main refrigerant pipe and the first branch refrigerant pipe and open the second branch refrigerant pipe when the second storage compartment satisfies the preset temperature when sensed by the inner temperature sensors of the first and second storage compartments.
 7. The refrigerator according to claim 5, the refrigerator further comprising: a plurality of decompressors to decompress refrigerant circulating respective evaporators, the decompressors comprising: a first decompressor which is provided between the branching point and the first evaporator, a second decompressor which is provided on the first branch refrigerant pipe, and a third decompressor which is provided on the second branch refrigerant pipe, wherein the respective decompressors are provided to sequentially increase resistances according to a sequence of the first, second and third decompressors.
 8. The refrigerator according to claim 7, further comprising a fourth decompressor which is provided between the first and second evaporators.
 9. The refrigerator according to claim 8, further comprising a fifth decompressor which is provided between the second and third evaporators.
 10. The refrigerator according to claim 8, wherein a total sum of resistances of the first and fourth decompressors is smaller than that of the second decompressor.
 11. The refrigerator according to claim 9, wherein a total sum of resistances of the first, fourth and fifth decompressors is smaller than that of the third decompressor.
 12. The refrigerator according to claim 7, wherein each decompressor comprises a capillary tube.
 13. The refrigerator according to claim 7, wherein the controller controls the selection valve to open the main refrigerant pipe and the first and second branch refrigerant pipes when the respective storage compartments perform the cooling operation, to close the main refrigerant pipe and open the first and second branch refrigerant pipes when the first storage compartment satisfies the preset temperature, and to close the main refrigerant pipe and the first branch refrigerant pipe and open the second branch refrigerant pipe when the second storage compartment satisfies the preset temperature, when sensed by the inner temperature sensors of the first and second storage compartments.
 14. A refrigerator comprising a compressor and a condenser, the refrigerator further comprising: first, second and third evaporators; a branching part which is provided at an outlet of the condenser; a first refrigerant path which is branched from the branching part to be connected with the first, second and third evaporators in series; a second refrigerant path which is branched from the branching part to be connected with the second and third evaporators in series; and a third refrigerant path which is branched from the branching part to be connected with the third evaporator.
 15. The refrigerator according to claim 14, wherein the first, second and third refrigerant paths comprise first, second and third decompressors, respectively, of which resistances are increased in sequence.
 16. The refrigerator according to claim 15, further comprising: a fourth decompressor which is provided between the first evaporator and the second evaporator, and a fifth decompressor which is provided between the second evaporator and the third evaporator, and wherein a resistance of the second decompressor is larger than a total sum of resistances of the first and fourth decompressors.
 17. A method of controlling a refrigerator having a main body which comprises first, second and third storage compartments of which preset temperatures are lowered in sequence, a compressor and a condenser which are provided in the main body, and first, second and third evaporators which are provided corresponding to the respective storage compartments, the method comprising: providing a main refrigerant pipe connecting the first, second and third evaporators in series, and at least one branch refrigerant pipe which is branched from an inlet of the first evaporator to be connected with an inlet of one of the second and third evaporators; sensing inner temperatures of the respective storage compartments; and opening and closing the main refrigerant pipe and the at least one branch refrigerant pipe not to supply a refrigerant to a respective evaporator corresponding to a respective storage compartment, when the sensed inner temperature of the respective storage compartment satisfies a preset temperature thereof.
 18. The method according to claim 17, wherein the providing the at least one branch refrigerant pipe comprises: providing a first branch refrigerant pipe which is branched from the inlet of the first evaporator to be connected with an inlet of the second evaporator, and a second branch refrigerant pipe which is branched from a branching point of the first branch refrigerant pipe to be connected with an inlet of the third evaporator.
 19. The method according to claim 18, wherein the opening and closing the main refrigerant pipe and the respective branch refrigerant pipes comprises: opening the main refrigerant pipe and closing the first and second branch refrigerant pipes when the compressor is driven; closing the main refrigerant pipe and the second branch refrigerant pipe and opening the first branch refrigerant pipe when the sensed inner temperature of the first storage compartment satisfies a preset temperature; and closing the main refrigerant pipe and the first branch refrigerant pipe and opening the second branch refrigerant pipe when the sensed inner temperature of the second storage compartment satisfies a preset temperature thereof.
 20. The method according to claim 19, wherein the opening and closing the main refrigerant pipe and the respective branch refrigerant pipe comprises: providing a first decompressor which is provided at the inlet of the first evaporator, a second decompressor which is provided on the first branch refrigerant pipe and a third decompressor which is provided on the second branch refrigerant pipe, having resistances of the first, second and third decompressors that increase in sequence; opening the main refrigerant pipe and the first and second branch refrigerant pipes when the compressor is driven; closing the main refrigerant pipe and opening the first and second branch refrigerant pipes when the sensed inner temperature of the first storage compartment satisfies a preset temperature thereof; and closing the main refrigerant pipe and the first branch refrigerant pipe and opening the second branch refrigerant pipe when the sensed temperature of the second storage compartment satisfies a preset temperature thereof.
 21. A method of controlling a refrigerator having a plurality of storage compartments, a plurality of evaporators corresponding to the plurality of storage compartments, and a condenser and compressor, the method comprising: setting preset temperatures for the storage compartments; connecting the evaporators, the condenser and the compressor in series via a main refrigerant pipe; connecting inlets of the evaporators to one another via at least one branch refrigerant pipe; sensing inner temperatures of the storage compartments; and opening and closing the main refrigerant pipe and the at least one branch refrigerant pipe to not supply refrigerant to a respective evaporator corresponding to a respective storage compartment when the sensed inner temperature of the respective storage compartment satisfies a preset temperature thereof. 